同学你好,
这道题其实没有涉及到小数和百分数的问题,选项根据的是题干中的这句话:“He also believes that for each 1 percent increase in pre-offer price adjustment, the initial return will increase by less than 0.5 percent”
即X增加1%,Y增加不到0.5%。两边百分号同时消掉后,就是X增加1,Y增加不到0.5. 也就是备择假设为Ha:bj<0.5,进而得到正确选项为C。